Blown Banshee... again... =(

[FIRST BANSHEE]

6th gear WOT,exhaust side seized...that's a lean condition. but you also need bigger carbs to get that engine to run right. I think the biggest main is a 400, so you still have room there, but I think you would benefit more from a bigger set of carbs.

I also agree that you need 50-50 race fuel

I also agree on the squish band, I believe if your under .040 you'll have problems with proper combustion.

now your looking at a set of pistons, sleeves and labor. could probably get some cubs for a few dollars more. good luck

[fast500#12]

that is a heat seize from over heating and if it has happened repeatedly the same way. i would look at your water pump first thing. you can tell by the way the piston from 3 months ago is rounded off on the exhuast side. you may be running a bit lean which is speeding along the process of heat siezing. that is kind what my pistons looked like when the blades melted off my impellar. i see you have a high flow impellar check the plastic gear that drives it. good luck.

[gipperz]

Make sure those v-force reeds are sealing good, I've been told that they sometimes don't seal to good and you need to use something like yamabond on them. Good luck to you.

[j28d]

Hey, are your intake boots cracked? My banshee came with a boost bottle and I couldn't figure out why one side then the other would be lean. Turned out the bottle vibrated too much and cracked the boots, but you really couldn't tell until they were off the bike and you pushed on the hole.

[Banshee_Guy]

The second pic from 2 months ago looks a little on the lean side. The second blow looks like it dove into the exhaust. Make sure you have good chamfer on the top of the exhaust port so its a smooth transition.

 

As for the floats... if they are set too low, it will not let enough fuel into the bowl and cause you to lean out, especially when full throttle!! If the float is too low it will close off the valve too early and not let the ride amount of fuel into the bowl.

 

TO adjust the float you take off the bowl, put the carb right side up and start flipping it over very slowly untill you notice the valve is closed. Take a measurement and adjust it accordingly with the little metal tab!

 

Have fun!

[Banshee_Guy]

One more thing. If you are ported and polished with a shaved head... those are the two biggest increases in heat! Get yourself a cool head and increase your reliability by 100%... specially with a stock rad that has a hard time cooling a stock machine!

[canyncarvr]

A couple of things missed from the beginning.....and that's what got you here.

 

It's 'ported'? What does that mean? Nothing. There are so many different types of porting AND folks that do it, saying it is 'ported' means nada.

 

Who am I? Nobody that you know...so do some research on what viable tuners/builders say (Oh...of course it's a given that EVERYbody is a 'good' builder, 'eh? That's funny!).

 

I don't know that ALBA is well thought of on this board or not...but chances are they know more about Banshees than your average backyard tuner.

 

From their website:

Good porting can give you the greatest power increase of any modification to your Banshee, while bad porting, well, stinks.

 

And (regarding combustion chamber pressure)...

We recommend anywhere from 150-160 lbs. for a stock motor, and from 140-145 lbs for a ported motor.

 

So...what you're running is (was) basically a grenade-job! You BUILT the thing to blow up!!

 

150lbs STATIC!!! (do you know what that means? It's different from 'dynamic'..and a 2-stroke engine's internal pressures are VERY dynamic!) chamber pressure, 4

[sheefreak]

It looks like someone started it up and ran it balls out w/o being warmed up, or your machine work is off. Looks like it cold siezed.

[FIRST BANSHEE]

A couple of things missed from the beginning.....and that's what got you here.

 

It's 'ported'?  What does that mean?  Nothing.  There are so many different types of porting AND folks that do it, saying it is 'ported' means nada.

 

Who am I?  Nobody that you know...so do some research on what viable tuners/builders say (Oh...of course it's a given that EVERYbody is a 'good' builder, 'eh?  That's funny!).

 

I don't know that ALBA is well thought of on this board or not...but chances are they know more about Banshees than your average backyard tuner.

 

From their website:

Good porting can give you the greatest power increase of any modification to your Banshee, while bad porting, well, stinks.

 

And (regarding combustion chamber pressure)...

We recommend anywhere from 150-160 lbs. for a stock motor, and from 140-145 lbs for a ported motor.

 

So...what you're running is (was) basically a grenade-job!  You BUILT the thing to blow up!!

 

150lbs STATIC!!! (do you know what that means?  It's different from 'dynamic'..and a 2-stroke engine's internal pressures are VERY dynamic!) chamber pressure, 4

[als660r]

my son blew his up twice pistons looked like yours

we found the GOOD rad was plugged

engine was getting hot

[vdubn]

I have been told by a very reputable Banshee engine builder in my area, that Banshee's in general self destruct while running WOF in top gear if held there longer than 5 seconds. Just curious how long you were at WOT in top gear, each of the times the engine blew?

 

For me, I'm never in top gear more than a second or two, if at all, but I do mostly dune riding, so that may be why.

 

Good luck with figuring out the issue, I'm interested to see what you find out.

[FIRST BANSHEE]

I have been told by a very reputable Banshee engine builder in my area, that Banshee's in general self destruct while running WOF in top gear if held there longer than 5 seconds.  Just curious how long you were at WOT in top gear, each of the times the engine blew?

 

For me, I'm never in top gear more than a second or two, if at all, but I do mostly dune riding, so that may be why.

 

Good luck with figuring out the issue, I'm interested to see what you find out.

488306[/snapback]

I run WOT in 6th all the time for longer than 5 sec when i'm on the road or fast trails.

[rocketboy]

A couple of things missed from the beginning.....and that's what got you here.

 

It's 'ported'?  What does that mean?  Nothing.  There are so many different types of porting AND folks that do it, saying it is 'ported' means nada.

 

Who am I?  Nobody that you know...so do some research on what viable tuners/builders say (Oh...of course it's a given that EVERYbody is a 'good' builder, 'eh?  That's funny!).

 

I don't know that ALBA is well thought of on this board or not...but chances are they know more about Banshees than your average backyard tuner.

 

From their website:

Good porting can give you the greatest power increase of any modification to your Banshee, while bad porting, well, stinks.

 

And (regarding combustion chamber pressure)...

We recommend anywhere from 150-160 lbs. for a stock motor, and from 140-145 lbs for a ported motor.

 

So...what you're running is (was) basically a grenade-job!  You BUILT the thing to blow up!!

 

150lbs STATIC!!! (do you know what that means?  It's different from 'dynamic'..and a 2-stroke engine's internal pressures are VERY dynamic!) chamber pressure, 4

[sredish]

I kind of agree. First off, the compression plus advanced timing might be close, but I don't see the lean / predet on the piston so much.

 

I say, can the head. Instead of repeatingly spending money on the top end, this time, hit up Dave Noss at Noss Machine and get a head from him with the proper domes to be sure the head is right. Also, how are you breaking these top-ends in?

 

Regarding this static and dynamic crap, this isn't a 4-stroke. We don't have cams affecting compression. That's basically what that is. You can have a "x-compression piston" but you can lose actual combustion compression with one cam and gain it with a second, hence the static AND dynamic, so you can decipher what's going on in the engine. This 2-stroke motor has, simply compression. Sure, porting can affect the compression some, but when it's said and done, your compression is what you have.

 

I've ran these twin motors up to 210 pounds with +7 degrees advanced, no problems. I have a buddy on an .080 top end running 205 pounds with a coolhead, squish is right on, close but still good and his motor is one hell of a runner, not "built to blow".

[2twin350s]

if the same cylinder keeps blowing,and by the looks of the piston,i would have to say it looks like the rings are clipping the exhaust port.make sure all your ports are shaved to keep a smooth transition to you cylinders.other than that,maybe your crank is goin out.but it did not look like that was happening.